Hi, Based on the information provided, there are several potential causes for the gradual weight reduction experienced by the patient. The symptoms of secondary amenorrhea, lower abdominal pain, and vaginal infections may suggest a hormonal imbalance or another reproductive health issue. Additionally, the patient s allergy to sunlight may indicate a possible autoimmune disorder or other systemic condition. The normal FSH, LH, TSH, and estrogen levels suggest that there may not be a hormonal imbalance causing amenorrhea. However, the fact that the patient has not had a withdrawal bleed with estrogen and progesterone suggests that there may be an issue with the endometrial lining or a possible structural issue with the uterus. Given the patient s history of MTP and tubectomy, there may be scarring or other damage to the uterus that is preventing proper menstrual bleeding. The normal USG may not have been able to identify such damage. The patient needs to undergo further diagnostic testing, such as a hysteroscopy or laparoscopy, to determine the underlying cause of amenorrhea and weight loss. Treatment will depend on the underlying cause but may involve hormonal therapy or surgical intervention. The patient should also receive supportive care and counseling to address any emotional or psychological impacts of the symptoms. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Priyanka, General & Family Physician